Method for selecting a wireless communication service provider in a multi-service provider environment

ABSTRACT

A communication device locates a wireless service provider in a multi-service provider environment using a frequency band search schedule. The frequency band search schedule has a first or home band and a several other frequency bands in a predetermined ordered. The order of the frequency bands may be programmed by the user or by a home service provider over the air. The communication device searches for an acceptable service provider by examining the home band and then the other bands listed in the frequency band search schedule. The bands are examined in the order specified by the frequency band search schedule. An acceptable service provider is identified by comparing the identify of a service provider specified by an identifier received from a band being examined with a list of acceptable service providers.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to communications; morespecifically, communications in a multi-service provider environment

[0003] 2. Description of the Related Art

[0004]FIG. 1 illustrates a portion of the radio frequency spectrum.Frequency range centered around 800 MHz has historically been known asthe cellular frequency range and frequency range centered about 1900 MHzis a newer defined frequency range associated with personalcommunication services (PCS). Each range of frequencies, i.e., thecellular and PCS, are broken into two portions. In cellular frequencyrange, there is uplink portion which is used for communications from amobile communication device to a base station such as a cellular basestation. Portion of cellular frequency range is used for downlinkcommunications, that is, communications from a cellular base station toa mobile communication device. In a similar fashion, Portion of PCSfrequency range is used for uplink communications, that is,communications from a mobile communication device to a base station.Portion of PCS frequency range is used for downlink communications,i.e., communications from a base station to a mobile communicationdevice.

[0005] Each of the frequency ranges are broken into bands which aretypically associated with different service providers. In the case ofcellular frequency range frequency bands and are designated band “a” foruplink and downlink communications, respectively. In a particulargeographic area, a cellular service provider is assigned frequency band“a” in order to carry out mobile communications. Likewise, in the samegeographic area another cellular service provider is assigned frequencybands (uplink) and (downlink) which arm designated band “b”. Thefrequency spectrums assigned to the service providers are separated soas to not interfere with each other's communications and thereby enabletwo separate service providers to provide service in the same geographicarea. Recently, the US Government auctioned the PCS frequency spectrumto service providers. As with the cellular frequency range, the PCSfrequency range is broken into several bands where a different serviceprovider may use a particular frequency band for which it is licensedwithin a particular geographical area. The PCS bands are referred to asA, B, C, D, E and F. The A band includes uplink band 50 and downlinkband 52. The B band includes uplink band 54 and downlink band 56. Band Cincludes uplink band 58 and downlink band 60. Each uplink and downlinkband of the A, B and C bands are approximately 30 MHz wide. The D bandincludes uplink band 62 and downlink band 64. The E band includes uplinkband 66 and downlink band 68. Likewise, band F includes uplink band 70and downlink band 72. The uplink and downlink bands of bands D, E and Fare approximately 10 MHz wide each. It should be noted that with thecellular and PCS frequency bands, it is possible to have as many aseight different wireless communication service providers in a particulararea.

[0006] Each of the different cellular and PCS bands consist of controlchannels and is communication channels in both the uplink and downlinkdirection. In the case of analog cellular bands, there are 21 controlchannels for both the “a” and “b” bands. Each of the control channelsinclude an uplink and a downlink portion. The control channels transmitinformation such as an SOC (System Operator Code), an SID (SystemIdentifier Code), paging information call setup information and otheroverhead information such as information relating to registering withthe mobile communication system. The portion of the cellular band'sspectrum not occupied by the control channels is used for communicationchannels. Communication channels carry voice or data communications,where each channel consists of an uplink and downlink communicationslink. Presently there are several cellular communication standards. Ananalog standard known as EIA/TIA 553 was built upon the AMPS (AdvancedMobile Phone Service) standard. This standard supports 21 analog controlchannels (ACC) and several hundred analog voice or traffic channels(AVC). A newer standard is the EIA/TIA IS54B standard which supportsdual mode operation. Dual mode operation refers to having an analogcontrol channel, and either an analog voice/traffic channel or a digitaltraffic channel (DTC). The AVC or DTC are used for actualcommunications, and the ACC is used to transfer information relating to,for example, call set-ups, service provider identification, and theother overhead or system information.

[0007] A newer standard, the EIA/TIA IS136 standard supportscommunications covered by both analog and dual mode cellular, and alsoincludes a totally digital communication scheme which was designed forthe PCS frequency bands A-F and cellular frequency bands “a” and “b”.This standard allows for a digital traffic channel (DTC) and a digitalcontrol channel (DCCH). In the case of the DTC, not only is the voice ordata communicated, but in addition, a digital channel locator (DL) istransmitted in the DTC. The DL enables a mobile communication devicethat locks onto the DTC to use the information in the DL to locate aDCCH for purposes of obtaining information such as the SOC, SID, paginginformation, and other system overhead information carried on thedigital control channel.

[0008] When a mobile communication device such as a mobile telephoneattempts to register with the service provider, it locks onto a controlchannel and reads information such as the SOC and SID. If the SOC and/orSID correspond to a service provider with which the user has acommunication services agreement, the telephone may register with theservice provider's mobile communication system via the up-link controlchannel.

[0009]FIG. 2 illustrates a map of the United States illustrating citiessuch as Seattle, Chicago and Washington, D.C. For example, in Seattlefrequency band A has been licensed to SOC (Service Operator Code) 001with a SID of 43 and band C has been licensed to SOC 003 with a SID of37. In Chicago, suppose that frequency band C has been licensed to SOC001 with a SID equal to 57, and that band B has been licensed to SOC 003with a SID of 51. In Washington, D.C. suppose that frequency band “a”has been licensed to a SOC 001 with a SID of 21, and that band A hasbeen licensed to SOC 003 with a SID of 17. It should be noted that thesame SOC may be found in several different locations although ondifferent frequency bands. It should also be noted that the same SOCwill be associated with different SIDs in each geographical area andthat in the same geographic area different service providers havedifferent SIDs. If a particular subscriber to a wirelesstelecommunication service has an agreement with a service providerhaving a SOC of 001, that subscriber would prefer to use systems with aSOC of 001 because the subscriber is likely to receive a less expensiverate. When the subscriber is in Seattle he/she would prefer to be onband A, and if in Chicago on band C, and if in Washington, D.C. on band“a”. The above described situation presents a problem for a wirelesscommunication service subscriber. As a subscriber moves from one area ofthe country to another, the telephone when turned on, searches for the“home” service provider, or the service provider with which thesubscriber has a pre-arranged agreement. If for example, the subscribertravels from Seattle to Chicago, when turning the phone on in Chicago,the phone will search through the different bands of the spectrum toidentify the service operator with the code 001 in order to find thedesired service provider.

[0010] In order to find a particular service provider, the phone mayhave to search through both the “a” and “b” cellular bands, and throughthe eight PCS bands. It should be recalled that there are up to 21different ACCs in each of the “a” and “b” cellular bands. It may benecessary to check 42 ACCS in order to find an ACC from which a SOC orSID may be obtained. Additionally, searching for a particular SOC or SIDin PCS bands A through F is particularly time consuming. The digitalcontrol channels (DCCHs), which contain the SOC and SID, are notassigned to specific frequencies within a particular PCS band. As aresult, the mobile communication device may find it necessary to searchthrough the spectrum of each PCS band looking for a DCCH, or an activeDTC that has a digital channel locator (DL) which will direct the mobilecommunication device to the DCCH. As illustrated above, the process ofsearching for a particular service provider is laborious and may requirea period of time on the order of several minutes.

SUMMARY OF THE INVENTION

[0011] An embodiment of the present invention provides a method forlocating a particular or desirable communications service provider in anenvironment having a plurality of service providers. After power-up, amobile communications device such as a cellular telephone, checks themost recently used control channel to determine whether an optimalservice provider is available on that channel. If an optimal serviceprovider is not available or if that channel is not available, themobile communication device performs a search through frequency spectrumin a pre-determined order until an optimal or acceptable serviceprovider is located.

[0012] In another embodiment of the invention, the frequency spectrum issearched in a pre-determined order that changes based on informationentered by a mobile communication device distributor or mobilecommunication device user. In yet another embodiment of the invention,the predetermined order for searching the spectrum for service providersis updated by over the air programming. In still another embodiment ofthe present invention, the predetermined order for searching is based onthe mobile communication device's operational history.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013]FIG. 1 illustrates the frequency spectrum used for wirelesscommunications;

[0014]FIG. 2 illustrates service areas within the United States;

[0015]FIG. 3 is a block diagram of a mobile communication device;

[0016]FIG. 4 is a flow chart illustrating a spectrum searching routine;

[0017]FIG. 5 is a flow chart illustrating the global spectrum searchroutine;

[0018]FIG. 6 is a flow chart illustrating a periodic search routine;

[0019]FIG. 7 is a flow chart illustrating a received signal strengthsearch routine;

[0020]FIG. 8 illustrates a search schedule; and

[0021]FIG. 9 illustrates a prioritized list of service providers.

DETAILED DESCRIPTION OF THE INVENTION

[0022]FIG. 3 illustrates a block diagram of a mobile communicationdevice such as a cellular telephone or personal communication device.Mobile communication device 10 includes transceiver 12 which sends andreceives signals from antenna 14. Mobile communication device 10 iscontrolled by control system 14 which may include a microprocessor or amicrocomputer. Control system 14 uses memory 16 for storing programsthat are executed and for storing information that is entered by theuser, the distributor, the communication services provider or themanufacture. Information such as user preferences, user telephonenumbers, preferred service provider lists and frequency search schedulesare stored in memory 16. Memory 16 may include storage devices such asrandom access memory (RAM), read only memory (ROM) and/or programmableread only memory (PROM). A user communicates with control system 14 viakeypad 18. Control system 14 communicates information to the user viadisplay 20. Display 20 may be used to display information such as statusinformation and items such as telephone numbers entered via keypad 18.Sound information to be transmitted from the mobile communication device10 is received via microphone 22, and sound communications received bymobile communication device 10 are played to the user via speaker 24.

[0023] After initially powering-up, a mobile communication devicelocates a service provider and registers with the service provider.Recalling FIG. 1, service providers are located at a plurality offrequency bands across the radio spectrum. In order to find a serviceprovider, the communication device searches the spectrum to find serviceproviders. The communications device examines received service providercode e.g., SOCs (Service Operator Code) or SIDs (System IdentificationCode) to determine whether the service provider is an optimal, preferredor prohibited service provider.

[0024]FIG. 4 illustrates a process or program that control system 14executes in order to find a desirable service provider. After power-up,step 30 is executed to initialize a non-optimal flag by clearing theflag. Step 32 determines whether the last service provider, that is, theservice provider used before powered down, was an optimal serviceprovider. This is determined by checking the SOC or SID of the lastservice provider and determining whether that service provider's SOC orSID corresponds to the SOC or SID) of an optimal service provider. TheSOC or SID of the last service provider and a list of optimal andpreferred service providers is stored in memory 16. If in step 32 it isdetermined that the prior service provider was not optimal, a globalspectrum search is executed. If the last service provider was optimal,step 34 is executed where system 14 attempts to lock, onto the controlsignal of the service provider. If the lock is unsuccessful, which mayindicate that that control channel is no longer available or out ofrange, the global spectrum search is executed. If a lock is successful,step 36 is executed. In step 36, it is determined whether the controlchannel contains the SOC or SM of an optimal service provider. Onceagain, this is determined by comparing the SOC or SID from the controlsignal with a list of optimal service provider SOCs or SIDS. If the SOCor SID does not belong to that of an optimal service provider, theglobal spectrum search 33 is executed and the identity of the frequencyband in which the non-optimal SOC or SID was located is passed to globalsearch routine 33 so as to avoid unnecessarily searching this portion ofthe spectrum again. If in step 36 it is determined that an optimalservice provider has been located, step 38 registers communicationdevice 10 with the service provider. Step 40 is an idle state wherecontrol system 14 simply monitors the control channel of the serviceprovider for communication system overhead information and for paginginformation that may indicate an incoming communication. While in idlestate 40, a timer is activated which permits a low-duty cycle search tobe performed if the phone is presently registered in a non-optimalservice provider system. This situation may arise if global spectrumsearch 33 provides a preferred but not optimal service provider.Periodically, such as every 5 minutes, step 42 is executed to determinewhether the non-optimal flag has been set, if the non-optimal flag isnot sets control system 14 returns to idle step 40. If the non-optimalhas been set, step 42 leads to the execution of periodic search routine44 where a search is conducted in order to attempt to locate an optimalservice provider. If periodic search routine 44 produces an optimalservice provider, the non-optimal service provider flag is cleared andthe mobile communication device registers with the optimal serviceproviders while executing periodic search routine 44. The mobilecommunications device then enters an idle state by executing step 40. Ifan optimal service provider is not located in routine 44, control system14 returns to an idle state by executing step 40.

[0025]FIG. 5 illustrates a flowchart of global spectrum search routine33 which is executed by control system 14. At step 60 it is determinedwhether the last control channel used by the mobile communication devicewas a personal communication services related control channel, that is,a control channel in the bands A through F. If the last control channelwas not a PCS control channel, step 62 is executed. In step 62 it isdetermined whether the mobile communication device can lock onto, orreceive and decode the last ACC (Analog Control Channel) that was used.If the mobile communication device can successfully lock onto the lastACC, step 64 is executed. If the communication device cannot lock ontothe last ACC, step 66 is executed. In step 66, an RSS (Received SignalStrength Scan) is performed. This step involves the mobile communicationdevice tuning to each of the 21 ACCs associated with the cellular bandof the last used ACC, and attempting to lock onto the strongest receivedsignal. In step 68, it is determined whether a lock has been achieved.In step 68 if a lock is not obtained, a predetermined search schedule isexecuted in order to find a service provider, if in step a lock isobtained, step 64 is executed where the SOC or SID obtained from thecontrol channel is compared to a list of optimal SOCs or SIDs. In step70 if the received SOC or SID is associated with an optimal serviceprovider, step 72 is executed where the mobile communication deviceclears the non-optimal flags, registers with the communication serviceprovider, and then enters an idle state by executing step 40 of FIG. 4.If, in step 70 it is determined that an optimal service provider SOC orSID was not received, step 74 is executed where the identity of thefrequency band just searched is stored in memory 16. Step 78 is executedafter step 74, after 68 if a lock is not obtained, or after step 60 ifthe last control signal was from a PCS frequency band. In step 78, asearch schedule is downloaded using a master search schedule. Whendownloading the search schedule in step 78, frequency bands previouslysearched are removed from the downloaded schedule so as to avoidsearching bands that have already been searched. For example, bandssearched in the search routine discussed with regard to FIG. 4 and thecellular band search discussed with regard to step 74 are removed fromthe search schedule. After the modified search schedule has been loadeda search pointer is initialized to point to the first band identified bythe modified search schedule. The first band identified on the modifiedschedule is searched with regard to received signal strength (RSS) instep 79's RSS routine. In the case of bands “a” and “b”, the ACC withthe strongest signal is selected. In the case of the PCS bands, that isthe bands A through F, 2.5 MHz sections of each band are searched in 30kilohertz steps. The mobile communication device tunes to the strongestsignal that crosses a minimum threshold, e.g., −110 dBm, within the 2.5MHz band being examined. In step 80 it is determined whether the signalis valid, that is, conforms to one of the above mentioned standards. Ifit is not valid, the search pointer is incremented in step 96, and ifthe signal is valid, step 82 is executed. In step 82 it is determinedwhether the sign is an ACC. If the signal is an ACC, the SOC or SID isdecoded in step 90. If the signal is not an ACC, step 84 determineswhether the received signal is a digital traffic channel (DTC) or adigital control channel (DCCH). If the signal is an DCCH the SOC or SIDis extracted in step 90. If it is determined that the received signal isa DTC, step 86 is executed where the DL (digital channel locator) isextracted to identify the location of the DCCHs associated with the DTCthat has been received. In step 88, the mobile communication devicetunes to the strongest DCCH of the digital control channels identifiedby the DL. In step 90, the SOC or SID of the received DCCH is extractedand in step 91, it is determined whether the SOC or SID is associatedwith an optimal service provider. If the SOC or SID is associated withan optimal service provider, step 92 clears the non-optimal flag andstep registers the mobile communication device with the serviceprovider. After step the communication device enters the idle state instep 40 of FIG. 4. If in step it is determined that the SOC or SID doesnot belong to that of an optimal service provider, step 94 is executedwhere the SOC or SID is stored in memory 16 indicating whether the SOCor SID was at least a preferred rather than an undesirable or prohibitedservice provider with the spectral location of the SOC's or SID'scontrol channel. In step 96 the search pointer that identifies the bandbeing searched is advanced to identify the next band in the schedule forsearching. In step 98 it is determined whether the pointer has reachedthe end of the search schedule. If the end of the search schedule hasnot been reached, step 82 is executed to perform another received signalstrength starch routine as discussed above, and if the last frequencyband has been searched step 100 is executed. In step 100 the mobilecommunication device registers with the best stored SOC or SID, that is,an SOC or SID that has at leas been associated with a preferred serviceprovider. The best service provider can be identified by comparing thestored SOCs or SIDs with a list of preferred SOCs or SIDs. The list ofpreferred SOCs or SIDs can include the optimal SOC(s) or SID(s) and aprioritized list of preferred SOCs or SIDs where the higher prioritywill get preference for registration. The listing also includesundesirable or prohibited SOC(s) or SID(s) that are used only inemergencies (e.g., 911 calls) or if the user enters an override command.After registering with the service provider in step 100, step 102 isexecuted to set the non-optimal flag, and then step 40 of FIG. 4 isexecuted where the mobile communication device enters the idle state.

[0026] It should be noted that the searching operation of FIGS. 4 and 5may be carried out in a simplified manner. With regard to FIG. 4,control system 14 may execute step 33 after step 30 while alwaysskipping steps 32, 34, 36 and 38. With regard to FIG. 5, control system14 may start the global spectrum search with step 78 while alwaysskipping steps 60-74.

[0027]FIG. 6 illustrates a flowchart for the periodic search routineexecuted by control system 14. In step 120 it is determined whether theperiodic search flag has been set. If the periodic search flag has notbeen set, step 122 is executed where periodic search flag is set and thesearch schedule is initialized by loading the master search scheduleinto the search schedule used by the periodic search routine; however,the frequency band currently being received is not included in thesearch schedule used for the periodic search routine. Step 122 also setsa search pointer to the first band in the search schedule. In step 124 areceived signal strength search (RSS) routine is conducted. As in step79 of the global spectrum search routine of FIG. 5, step 124 is a RSSroutine of any PCS and cellular bands that are in the search schedule.In the case of a cellular band search, the 21 ACCs are searched using areceived signal strength search i.e., the transceiver tunes to thestrongest ACC. In the case of a PCS frequency band search, as discussedearlier, each band is broken into segments of approximately 2.5 MHzwhere a search of each segment is conducted in 30 kilohertz steps. Thestrongest signal within the 2.5 MHz segment and above a minimumthreshold, such as −110 dBm, is selected. In step 126 the selectedsignal is examined to determine if it is valid by conforming to one ofthe previously referenced standards. If the signal is invalid, step 144is executed and if the signal is valid, step 129 is executed. Step 129determines whether the signal is an ACC. If the signal is an ACC, step130 is executed when the SOC or SM is extracted and if the signal is notan ACC, step 132 is executed. Step 132 determines whether a DTC signalhas been received. If the signal is not a DTC signal (therefore it is aDCCH signal), step 130 is executed to extract the SOC or SID from theDCCH signal. If in step 132 it is determined that a DTC has beenreceived, step 134 is executed to extra the DL to enable tuning to aDCCH. In step 136 a received signal strength search is conducted of theDCCHs where the strongest signal is selected, and then step 130 isexecuted to extract an SOC or SID from the signal. In step 138 it isdetermined whether the SOC or SID is an optimal SOC or SID. If the SOCor SID is optimal, step 140 clears the non-optimal flag and in step 142the mobile communication device registers with the service providerassociated with the optimal SOC or SID. Step 40 of FIG. 4 is thenexecuted to enter the idle state. If in step 138 it is determined thatthe SOC or SID was not an optimal service provider, step 144 isexecuted. In step 144 the search pointer is incremented to the next bandto be searched. In step 146, it is determined whether the entire searchschedule has been completed. If the schedule has not been completed step40 is executed so that the mobile communication device can be returnedto the idle state. If in step 146 it is determined that the searchschedule has been completed, step 148 clears the periodic search flagand then step 40 is executed so that the mobile communication device canenter the idle state.

[0028]FIG. 7 illustrates a flow chart of the RSS routine or receivedsignal strength search routine which is carried out, for example, insteps 79 of FIGS. 5 and 124 of FIG. 6. Step 170 determines whether theband being searched is one of the “a” or “b” cellular bands. If acellular band is being searched, step 172 is executed where the 21 ACCsare searched to determine which is the strongest, the strongest ACC istuned to by transceiver 12 under the control of control system 14 andthen the RSS routine is exited. If in step 170 it is determined that acellular band is not being search step 178 tunes transceiver 12 to thebeginning of the first 2.5 MHz band in the PCS band being searched. Step178 also clears a search scratch pad memory location in memory 16. Thesearch scratch pad is used to record the amplitude or strength andlocation of a received signal. In step 180 it is determined whether thesignal being received is greater than a threshold. If the signal isgreater than the threshold, step 182 is executed, if the signal is notgreater than the threshold, step 184 is executed. In step 182 itdetermined whether the received signal strength is greater than thesignal strength value stored in the search scratch pad. If the receivedsignal is not greater, then step 184 is executed. If the received signalstrength is greater, step 186 is executed and the present signalstrength is recorded in the search scratch pad with the receivedsignal's location in the spectrum. In step 184, transceiver 12 is tunedto a frequency 30 kilohertz higher than the frequency at which it wastuned. Step 188 determines whether the new frequency extends beyond the2.5 MHz band currently being searched. If the new frequency does notexceed the 2.5 MHz band, step 180 is executed to once again examinereceived signal strength relative to the signal strength or amplitudevalue stored in the search scratch pad. If in step 188 it is determinedthat the 30 kilohertz increment extends beyond the 2.5 MHz band beingexamined, step 190 is executed. In step 190, the transceiver tunes tothe signal location specified in the search scratch pad. If the signalis a valid signal and can be decoded, the RSS routine is exited. If thesignal is not valid or cannot be decoded, (e.g., the signal does notconform to the above-referenced standards) step 192 is executed. In step192, the transceiver is tuned to the beginning of the next 2.5 MHz bandwithin the PCS band being searched. Step 194 determines whether the new2.5 MHz band extends beyond the PCS band currently being searched. Ifthe new increment extends beyond the PCS band being searched, theperiodic search routine is exited. If the 2.5 MHz increase does notresult in extending beyond the PCS band being searched, step 196 isexecuted. In step 196, the search scratch pad containing signal strengthmeasurements and signal location information is cleared to prepare forsearching another band. After step 196, step 180 is executed asdescribed above.

[0029]FIG. 8 illustrates a master search schedule. The master scheduleis used to initialize search schedules used in the above describedsearch routines. The master search schedule is stored in a memory suchas memory 16. The master search schedule can be initially programmed bythe mobile communication device's manufacturer, distributor or user. Itshould be noted that the first location in the search schedule is leftunprogrammed. If left blank, the blank is ignored when initializing thesearch schedules for the search routines. It is desirable for the firstlocation to be programmed with the band in which the user's home serviceprovider resides. For example, if the user has a service agreement witha service provider who is licensed to operate in PCS band B within theSID or geographical area in which the user most frequently is located,band B is programmed into the first slot of the master search schedule.If, for example, band B is programmed in the first slot, the slotoriginally containing band B is made blank. This avoids searching thesame band twice. It should also be noted that the user can vary themaster search schedule through keypad 18. Additionally, the mastersearch schedule may be reprogrammed using signals received over thewireless communication channel. For example, the mobile communicationdevice may be restricted to accepting new programming for the mastersearch schedule only from a service provider transmitting the home SIDand an optimal SOC. It is also possible to accept over the airprogramming if the service provider sends a prearranged code. It isdesirable to restrict the over the air programming through the use ofcodes, home SIDs and/or optimal SOCs to avoid unintentional orundesirable altering of the master search schedule. Over the airprogramming may be implemented using for example, logical sub-channelsof a digital control channel. The logical sub-channels have thecapability to transmit data addressed to a particular mobilecommunication device and to receive data, such as confirmation data,from the mobile communications device.

[0030] When the search schedules are initialized using the master searchschedule, it is also possible to precede the first location in themaster search schedule with other frequency bands based on, for example,the prior history of the mobile communication device's use. For example,the first location searched may be the location where the phone was lastturned off (powered down) or the location where the phone was lastturned on (powered up).

[0031]FIG. 9 illustrates a table stored in memory 16 defining theoptimal service provider's SOC and SIDs, and preferred serviceprovider's SOCs and SIDS. The SOC or SID with the lowest number has thehighest priority and is preferred over service providers with highernumbers and therefore a lower priority. For example, an SOC or SID witha priority level 2 would be preferred over an SOC or SID with a prioritylevel of 5. The table may also include SOCs or SIDs that are undesirableor prohibited. In the case of SOCs or SIDs that are prohibited, it isdesirable to permit connection to the prohibited SOCs or SIDs when anemergency call such as a 911 call, is attempted or when the user entersan override command. The table in FIG. 9 may be programmed by themanufacturer, by the distributor when the phone is purchased or by theuser. It is also possible to program the table of FIG. 9 over the airusing restrictions similar to those used when programming the mastersearch schedule over the air.

What is claimed is:
 1. A wireless communication device that locates awireless service provider in a multi-service provider environment,comprising: a memory that stores a frequency search schedule having aplurality of frequencies in a prioritized order; and a processor thataccepts information, modifies the prioritized order of the frequencysearch schedule based on the information, and examines frequencies inthe modified order in the frequency search schedule, until a frequencyhaving a preferred service provider is located, if a last serviceprovider was not a preferred service provider.
 2. The wirelesscommunication device of claim 1, wherein the information accepted by theprocessor comprises information input by at least one of a devicedistributor and a device user.
 3. The wireless communication device ofclaim 1, wherein the information accepted by the processor comprisesinformation transmitted over-the-air.
 4. The wireless communicationdevice of claim 1, wherein a highest priority frequency in the frequencysearch schedule is a home frequency of the communication device.
 5. Thewireless communication device of claim 1, wherein the frequency searchschedule is in an order optimized to reduce a time necessary to locate apreferred service provider.
 6. The wireless communication device ofclaim 1, wherein the processor periodically examines frequencies in themodified frequency search schedule until a frequency having a preferredservice provider is located, if a determination is made that a presentservice provider is not a preferred service provider.
 7. The wirelesscommunication device of claim 1, wherein the processor locates a serviceprovider by dividing the frequencies into frequency bands, detecting asignal frequency with a largest amplitude in a frequency band, anddecoding an identifying signal transmitted at the detected frequency. 8.A method by which a communication device locates a wireless serviceprovider in a multi-service provider environment, the method comprising:storing a frequency search schedule having a plurality of frequencies ina prioritized order; determining that a last service provider was not apreferred service provider; accepting information; modifying theprioritized order of the frequency search schedule based on the acceptedinformation; and examining frequencies in the modified order until afrequency having a preferred service provider is located.
 9. The methodof claim 8, wherein accepting information further comprises acceptinginformation input by at least one of a device distributor and a deviceuser.
 10. The method of claim 8, wherein accepting information furthercomprises accepting information transmitted over-the-air.
 11. The methodof claim 8, wherein examining frequencies further comprises: a) dividingthe frequencies in the frequency search schedule into bands; b)selecting a first frequency band; c) detecting a signal frequency with alargest amplitude in the first frequency band; d) determining if anidentifying signal transmitted at the detected signal frequency can bedecoded; and e) if the identifying signal cannot be decoded, selecting anext frequency band.
 12. The method of claim 11, further comprising:repeating steps a) through e) until it is determined that theidentifying signal can be decoded; and decoding the identifying signalat the detected signal frequency, to identify a preferred serviceprovider.
 13. The method of claim 8, further comprising periodicallyexamining frequencies in the search schedule until a frequency having apreferred service provider is located, if a present service provider isnot a preferred service provider.
 14. The method of claim 8, wherein thefrequency search schedule is in an order optimized to reduce a timenecessary to locate a preferred service provider.
 15. A recording mediumthat stores a control program for use by a wireless communicationdevice, the control program including instructions for: storing afrequency search schedule having a plurality of frequencies in aprioritized order; determining that a last service provider was not apreferred service provider; accepting information; modifying theprioritized order of the frequency search schedule based on the acceptedinformation; and examining frequencies in the modified order until afrequency having a preferred service provider is located.
 16. Therecording medium of claim 15, the control program further includinginstructions for modifying the stored frequency search schedule based oninformation input by a device distributor, device user, or transmittedover-the-air.
 17. The recording medium of claim 15, the control programfurther including instructions for setting a flag if a present serviceprovider is not a preferred service provider.
 18. The recording mediumof claim 17, the control program further including instructions forperiodically examining frequencies in the search schedule until afrequency having a preferred service provider is located, if the flaghas been set.
 19. The recording medium of claim 15, the control programfurther including instructions for: a) dividing the frequencies in thefrequency search schedule into bands; b) selecting a first frequencyband; c) detecting the signal frequency with the largest amplitude inthe first frequency band; d) determining if an identifying signaltransmitted at the detected signal frequency can be decoded; and e) ifan identifying signal cannot be decoded, selecting a next frequencyband.
 20. The recording medium of claim 15, wherein the frequency searchschedule is in an order optimized to reduce a time necessary to locate apreferred service provider.